可以發現，添加一個教師的同時指定一個學生，這種方式相當糟糕，合理的方式應該是在添加學生的時候指定教師。即在學生類里指

定教師對象，配置文件里配置成many-to-one。

單純只使用many-to-one:
在Student類里加入Teacher teacher屬性。
注釋掉teacher.hbm.xml里的<set ...></set>內容
在student.hbm.xml里入many-to-one屬性：

[c-sharp]?view plaincopyprint?

<?xml?version="1.0"?>??

<!DOCTYPE?hibernate-mapping?PUBLIC??

????????"-//Hibernate/Hibernate?Mapping?DTD?3.0//EN"??

????????"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">??

<hibernate-mapping?package="com.sjtu.xw.pojo2">??

????<class?name="Student"?table="student">??

????????<id?name="id"?column="id">??

????????????<generator?class="native"></generator>??

????????</id>??

????????<property?name="stuName"?column="studentName"?length="30"?/>??

????????<many-to-one?name="teacher"?column="teacherId"?class="Teacher"??

????????????fetch="join"?lazy="false"?/>??

????????<!--??

????????????這里的column="teacherId"是指明了自身(student表)表里的teacherId屬性，指向teacher表的外鍵??

????????-->??

????</class>??

</hibernate-mapping>??

?

做完上述工作即可進行測試了：

Test2.java

[c-sharp]?view plaincopyprint?

package?com.sjtu.xw.test;??

import?java.util.List;??

import?org.hibernate.Session;??

import?org.hibernate.SessionFactory;??

import?org.hibernate.Transaction;??

import?com.sjtu.xw.pojo2.Student;??

import?com.sjtu.xw.pojo2.Teacher;??

import?com.sjtu.xw.util.HibernateUtil;??

public?class?Test2?{??

????public?static?void?main(String[]?args)?{??

????????Test2?test?=?new?Test2();??

????????//?test.addStudent();//通過??

????????//test.addTeacher();//通過??

????????test.test();??

????}??

????public?void?addStudent()?{??

????????Teacher?teacher?=?new?Teacher();??

????????teacher.setId(1);??

????????Student?student?=?new?Student();??

????????student.setStuName("student8");??

????????student.setTeacher(teacher);??

????????SessionFactory?sf?=?HibernateUtil.getSessionFactory();??

????????Session?session?=?sf.openSession();??

????????Transaction?tx?=?session.beginTransaction();??

????????session.save(student);??

????????tx.commit();??

????????session.close();??

????????sf.close();??

????}??

????public?void?addTeacher()?{??

????????Teacher?teacher?=?new?Teacher();??

????????teacher.setTeaName("Teacher5");??

????????SessionFactory?sf?=?HibernateUtil.getSessionFactory();??

????????Session?session?=?sf.openSession();??

????????Transaction?tx?=?session.beginTransaction();??

????????session.save(teacher);??

????????tx.commit();??

????????session.close();??

????????sf.close();??

????}??

????public?void?test()?{??

????????SessionFactory?sf?=?HibernateUtil.getSessionFactory();??

????????Session?session?=?sf.openSession();??

????????Transaction?tx?=?session.beginTransaction();??

????????List?list?=?session.createQuery("from?Student?s?where?s.id=1").list();??

????????Student?s?=?(Student)?list.get(0);//找student的id為1的學生，并獲取老師的信息。??

????//??System.out.println(s);??

????????System.out.println(s.getTeacher());??

????????System.out.println(s.getTeacher().getTeaName());??

????????tx.commit();??

????????session.close();??

????????sf.close();??

????}??

} ?

本文轉自xwdreamer博客園博客，原文鏈接：http://www.cnblogs.com/xwdreamer/archive/2010/12/01/2297065.html，如需轉載請自行聯系原作者

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